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AOPA's comments to Notice of Proposed Rulemaking 97-CE-67-ADAOPA's comments to Notice of Proposed Rulemaking 97-CE-67-AD

Federal Aviation Administration
Central Region—Office of the Regional Counsel
Attn: Rules Docket No. 97-CE-67-AD
601 East 12th St., Room 1558
Kansas City, MO 64106


The Aircraft Owners and Pilots Association (AOPA), representing the aviation interests of more than 350,000 pilots and aircraft owners, submits the following comments to Notice of Proposed Rulemaking (NPRM) 97-CE-67-AD. The NPRM proposes to supersede AD-75-23-08 R5, implement simplified inspection procedures, revise inspection intervals, and recommends removal of the exhaust system for detailed inspection at regular intervals.

AOPA thanks the FAA for rescinding the previously issued direct final rule and affording the public an opportunity to comment on the proposed provisions of this AD. Because of the technical nature of the issues surrounding this AD, AOPA has relied heavily on the operational and technical expertise of the Cessna Pilots Association (CPA) in the formulation of our comments. CPA’s contributions to this process are a shining example of how the knowledge and expertise of type clubs and owners’ organizations can aid the FAA in developing reasonable and affordable solutions to legitimate airworthiness concerns.

AOPA recognizes the severity of the safety issues surrounding twin Cessna exhaust system failures and agrees that appropriate actions should be taken to ensure continued safe operation of these aircraft. However, AOPA believes that the actions proposed by this AD are overly complex, may lead to additional safety problems, and will impose a significant financial hardship upon affected aircraft owners with little safety benefit.

Cost analysis

Upon the FAA’s request, AOPA solicited comments from affected aircraft owners regarding the utility and economic impact of the maintenance actions proposed in 97-CE-67-AD. We question the administrator’s certification that this rulemaking is not a “significant regulatory action” under Executive Order 12866. As defined in that order, a significant regulatory action is one that, among other things, has an annual effect on the economy of $100 million or more, or adversely affects in a material way a sector of the economy. From the limited analysis we have made, it is probable that any fair and complete calculation and analysis would conclude that this rule, if effected as proposed, would meet this definition.

The rulemaking itself estimates for the proposed initial inspections alone, that the cost on U.S. operators would be $4,340 per airplane ($28.210 million for the entire fleet) and admits that these figures do not take into account the cost of any repetitive inspections or repair/replacement parts. This analysis is incomplete without adding the cost of repairs and replacement parts, especially those necessitated by the proposed one-time disassembly inspection. The Cessna Pilots Association, after discussions with two of the three FAA designated repair stations named in the NPRM, estimates that at least 75 percent of the exhaust system components would be rejected and would need to be replaced. Consequently, CPA conservatively estimates that the cost of repairs and replacements required by the proposed inspections would be $73.125 million for the U.S. fleet. Realistically, many of the replacement parts will be required to be purchased from Cessna, which could easily double or triple any parts cost estimate.

Additionally, these figures do not include the cost impact of extended periods of aircraft “downtime” that will inevitably result from the actions proposed in this AD. A substantial number of affected aircraft owners use their aircraft as a source of revenue or in conjunction with small businesses. Most owners/operators estimate that downtime resulting from the proposed actions of this AD will cause a substantial loss in revenue from which their business may be unable to recover. Therefore, AOPA believes that any fair and reasonable calculation and cost analysis is likely to reveal that this rule, if adopted as proposed, would easily have an annual effect on the economy of $100 million or more. Additionally, such an analysis is likely to conclude that this rulemaking will adversely affect in a material way a sector of the economy.

Such a conclusion would necessitate a review of this rulemaking by the Office of Information and Regulatory Affairs of the Office of Management and Budget. In such a review, the office would honor the regulatory philosophy of the order that “federal agencies should promulgate only such regulations as are required by law, are necessary to interpret the law, or are made necessary by compelling public need.” AOPA hopes and expects that the office would conclude that this rulemaking does not satisfy this philosophy.

Technical issues

AOPA agrees with and supports CPA’s comments to Docket 97-CE-67-AD, dated August 3, 1999. To clarify AOPA’s position on the technical issues surrounding this AD, a listing of our major concerns follows:

  • Repetitive visual inspections and pressure tests are currently providing an appropriate level of safety.
  • Mandatory exhaust system inspections by three FAA-approved repair stations cannot be accomplished in the proposed two-year compliance period.
  • Inconel is not necessarily the material of choice for all exhaust system components.
  • Inconel exhaust components should be subject to the same repetitive visual inspection intervals and pressure tests as stainless steel components.
  • Repetitive tailpipe removal should apply to Inconel as well as stainless steel, and the interval should be accomplished every annual inspection.
  • Proposed minimum exhaust component wall thickness of .025 inch is inappropriate.
  • Airworthiness of exhaust system components can be established by A&P/IAs in the field. Exhaust repair stations should become involved only when repairs are necessary.
  • Proposed repetitive 500-hour disassembly of slip joints is unnecessary and may cause more harm than good.
  • Engine mount beam inspection provision requires clarification.
  • Prohibition of certain weld repairs requires clarification.

Note: For supporting information on the above listed items, refer to Cessna Pilots Association comments to Rules Docket 97-CE-67-AD dated August 3, 1999.

Comments on specific provisions of NPRM 97-CE-67-AD

AOPA agrees with and supports the section-by-section comments of the Cessna Pilots Association. For comments on specific provisions of the proposed AD, refer to Cessna Pilots Association comments to Docket 97-CE-67-AD dated August 3, 1999.

CPA proposed alternative method of compliance

AOPA supports the method of compliance proposed by CPA and strongly recommends that the FAA simplify the actions required by 97-CE-67-AD by implementing CPA’s proposed compliance actions. AOPA holds that the alternative actions recommended by CPA will adequately address all technical, logistical, and economic issues associated with this AD. Furthermore, AOPA believes this method is the most reasonable way to address the airworthiness issues surrounding turbocharged twin Cessna aircraft without imposing significant economic hardship upon owners of affected aircraft.

Note: For a summary of AOPA-supported alternative compliance actions, see Cessna Pilots Association comments to Rules Docket 97-CE-67-AD dated August 3, 1999.


AOPA holds that the provisions proposed in 97-CE-67-AD will cause significant inspection backlogs, a shortage of replacement parts, extended aircraft downtime, and place a substantial financial burden upon affected aircraft owners. Additionally, the safety record of the past 30 months clearly demonstrates that twin Cessna exhaust system failures can be effectively prevented through a combination of regular and diligent visual inspections and pressure tests. AOPA implores the FAA to consider all technical, logistical, and economic impacts of the actions proposed by this AD. AOPA recommends that the FAA replace the actions proposed in 97-CE-67-AD with the compliance actions proposed by Cessna Pilots Association.

Additionally, AOPA encourages the FAA to continue research into the use of fire detection/suppression equipment, or other technological remedies, as possible terminating action to the repetitive inspection requirements of the proposed AD.

Thank you for your time and consideration in this matter. AOPA stands ready to assist the FAA in reconsidering the actions proposed by this AD.


Dennis E. Roberts
Vice President/Executive Director
Government and Technical Affairs

August 6, 1999

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